1. Field of the Invention
The present invention relates to a rotating disc device.
A rotating disc device, such as a magnetic disc device or an optical disc device, is used as an external storage device.
Large size disc devices usually each contain in a casing called a locker, an aggregation of a plurality (for example, four or eight) of rotating disc devices, where each of the devices comprises a rotating disc, a head for writing and reading data on the disc, and positioning mechanism for positioning the head, and independently operating as a rotating disc device.
In particular, in a large computer system, a large number of rotating disc devices are aggregated, and therefore, decreases in the total scale of the aggregated disc devices, power consumption, and noise, are required.
2. Description of the Related Art
FIG. 1 shows the construction of a conventional aggregated magnetic disc system.
In FIG. 1, reference LK denotes a locker, reference numeral 1a and 1b each denote a disc enclosure containing a magnetic disc mechanism, 2a and 2b each denote a power amplifier, 3a and 3b each denote a power supply unit, 4a and 4b each denotes a control circuit, 5a and 5b each denote a first cooling fan, 6a and 6b each denote a second cooling fan, and 9a and 9b each denote a power cable.
In the construction of FIG. 1, the portion constituted by the components with the reference numerals including "a" such as "1a" or "2a", etc., and the portion constituted by the components with the reference numerals including "b" such as "1b" or "2b", etc., are each operated as an individual rotating disc device.
The magnetic disc mechanism contained in the disc enclosure 1a or 1b comprises a rotating disc as a storage medium, a head for writing and reading data on the disc, and positioning mechanism for positioning the head, and the disc is rotating driven by a spindle motor, and the positioning mechanism is driven by a voice coil motor.
The spindle motor and the voice coil motor are each driven by a driver circuit which is realized by the above power amplifier 2a or 2b.
The control circuit 4a or 4b each controls a corresponding magnetic disc mechanism.
The power supply unit 3a or 3b each supplies an electric power to a corresponding power amplifier 2a or 2b and a corresponding control circuit 4a or 4b.
The power cable 9a or 9b connects a corresponding power supply unit 3a or 3b and a corresponding control circuit 4a or 4b.
The first cooling fan 5a cools the disc enclosure 1a, the power amplifier 2a, and the power supply unit 3a, and the first cooling fan 5b cools the disc enclosure 1b, the power amplifier 2b, and the power supply unit 3b. The second cooling fan 6a cools the control circuit 4a, and the second cooling fan 6b cools the control circuit 4b. The flows of the air streams generated by the cooling fans 5a, 5b, 6a and 6b are shown in FIG. 2.
As shown in FIG. 1, all the above construction is contained in the locker LK, and the components of the construction are arranged into a multi-layered construction so that a high density assembly of the aggregation of the plurality of rotating disc devices is realized.
The above construction has, however, the following problems:
(1) the power cable connecting the corresponding power supply unit 3a or 3b and the control circuit 4a or 4b, occupies a large volume in the space of the locker LK; and
(2) the electric power is used ineffectively regarding the operation of the cooling fans.
The power supply units 3a and 3b each outputs low voltage (for example, +5 V, -5.2 V, .+-.12 V) currents and high voltage (for example, .+-.24 V) currents. The low voltage currents are mainly supplied to the control circuits 4a and 4b through the power cable 9a and 9b, respectively, and the high voltage currents are supplied to the power amplifiers 2a and 2b, respectively.
The low voltage currents supplied to the control circuits 4a and 4b are large, for example, 30A, and therefore, the power cables 9a and 9b must have a relatively large cross section. For example, a plain braided wire having a width of 3 cm, is used. Namely, the power cable 9a and 9b occupies a relatively large volume in the space of the locker LK.
Further, all the above components which are usually packed in the locker LK so as to realize a high density installation, however, some of the above components are installed movably because all the components must be accessible from the outside at the time of maintenance. The control circuit 4a or 4b is often one of the movably installed components, and therefore, a long cable is required for maintaining connection between the movable control circuit and the corresponding power supply unit even in the moved condition for maintenance. The long cable is folded when the movable components are packed in the condition of the high density installation. Namely, in the packed condition, a large volume is occupied by the folded long and thick cable connecting between the control circuits and the corresponding power supply units.
Regarding the effectiveness of the operation of the cooling fans, the control circuits 4a and 4b corresponding all magnetic disc mechanisms must always be in operating condition because the control circuit must communicate with an apparatus in the upper level even when the corresponding magnetic disc mechanism is not operated, and therefore, the power supply unit supplying electric power to the control circuit also must always operate. Thus, the first cooling fans 5a and 5b which cool the power supply units 3a and 3b together with the power amplifiers 2a and 2b and the disc enclosures 1a and 1b, must always operate even when the corresponding magnetic disc mechanism is not operated.
As the cooling fans 5a and 5b normally operates with a relatively high power for removing a relatively large amount of heat generated in the power amplifiers 2a and 2b, the power supply units 3a and 3b, and the disc enclosures 1a and 1b, a great amount of power is consumed ineffectively when the corresponding magnetic disc mechanism is not operated due to such a high power operation of the first cooling fans 5a and 5b.
Further, the above constant operation of the high-power cooling fans 5a and 5b causes a large noise even when the corresponding magnetic disc mechanism is not operated.
Thus, an effective operation of the cooling fans is required to solve the above problems.